[Lxc-users] Failed to access console after launching LXC through libvirt

unicell unicell at gmail.com
Thu Nov 8 16:30:23 UTC 2012 

On Fri, Nov 9, 2012 at 12:09 AM, unicell <unicell at gmail.com> wrote:

> Hi,
>
> I'm trying to manage LXC instances through OpenStack, which use libvirt as
> a virtualization driver layer. After launching LXC instance, I simply could
> not attach to the console.
>
> virsh # list
>  Id Name                 State
> ----------------------------------
> 14366 instance-00000078    running
>
> virsh # console 14366
> Connected to domain instance-00000078
> Escape character is ^]
>
>
> And it keeps stuck here.
>
> Initially I thought it could be a cgroup device config issue, and tried to
> "echo ‘c 5:1 rwm'
> >/cgroup/devices/libvirt/lxc/instance-00000078/devices.allow“, to add
> /dev/console access right to the container. But it does not work, console
> stilll not working.
>
> Before the cgroup tweaking, devices.list are as follows
>
> [root at localhost libvirt]# cat
> /cgroup/devices/libvirt/lxc/instance-0000007a/devices.list
>
> c 1:3 rwm
> c 1:5 rwm
> c 1:7 rwm
> c 1:8 rwm
> c 1:9 rwm
> c 5:0 rwm
> c 5:2 rwm
> c 136:* rwm
>
>
> I'm not quite sure what kind of issue could possibly cause this console
> access issue. Cause I'm now using two different guest OS templates on two
> different host OSes. Following are some symptoms I observed.
>
>
> * (g) for container guest OS
> * (h) for host OS
> * NOTE: Ubuntu guest os are generated by lxc-create -t ubuntu, which is an
> Ubuntu 12.04 based lxc template.
>              CentOS guest os are handcrafted by myself, taking reference
> of http://wiki.1tux.org/wiki/Lxc/Installation/Guest/Centos/6
>
>    1. Ubuntu (g) launched by lxc-start on Ubuntu 12.04 host, console works
>    2. Ubuntu (g) launched by OpenStack / libvirt on Ubuntu 12.04 host,
>    console works
>    3. Ubuntu (g) launched by OpenStack / libvirt on CentOS 6.3 host,
>    console NOT works
>    4. CentOS (g) launched by lxc-start on Ubuntu 12.04 host, console works
>    5. CentOS (g) launched by OpenStack / libvirt on Ubuntu12.04 host,
>    console NOT works
>    6. CentOS (g) launched by OpenStack / libvirt on CentOS 6.3 host,
>    console NOT works
>
> So somehow I feel it could be something related to LXC template rootfs,
> but Host OS do make a difference (2 vs. 3). lxc-start / libvirt also makes
> a difference (4 vs. 5), but that might be caused by cgroup setting.
>
> Could someone shed me some clues to further digging this issue? Thanks!
>
> --
> Qiu Yu
>

For the "Ubuntu (g) launched by OpenStack / libvirt on CentOS 6.3 host", I
also tried following command and console still not working.

echo "a *.* rwm"
>/cgroup/devices/libvirt/lxc/instance-00000078/devices.allow


More information attached.

[root at localhost ~]# ls -l
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty*
crw-rw-rw- 1 root tty 5, 0 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty
crw------- 1 root tty 4, 0 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty0
crw------- 1 root tty 4, 1 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty1
crw------- 1 root tty 4, 2 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty2
crw------- 1 root tty 4, 3 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty3
crw------- 1 root tty 4, 4 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty4
crw------- 1 root tty 4, 5 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty5
crw------- 1 root tty 4, 6 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty6
crw------- 1 root tty 4, 7 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty7
crw------- 1 root tty 4, 8 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty8
crw------- 1 root tty 4, 9 Oct 23 20:01
/home/stack/nova_state/instances/instance-00000078/rootfs/dev/tty9


[root at localhost ~]# cat
/cgroup/devices/libvirt/lxc/instance-00000078/devices.list
c 1:3 rwm
c 1:5 rwm
c 1:7 rwm
c 1:8 rwm
c 1:9 rwm
c 5:0 rwm
c 5:2 rwm
c 136:* rwm
c 5:1 rwm
c 5:* rwm
a *:* rwm


[root at localhost ~]# cat /etc/libvirt/lxc/instance-00000078.xml
<!--
WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
OVERWRITTEN AND LOST. Changes to this xml configuration should be made
using:
  virsh edit instance-00000078
or other application using the libvirt API.
-->

<domain type='lxc'>
  <name>instance-00000078</name>
  <uuid>55f225d1-e49c-4a51-9c17-0a5dde6d1917</uuid>
  <memory>524288</memory>
  <currentMemory>524288</currentMemory>
  <vcpu>2</vcpu>
  <os>
    <type arch='x86_64'>exe</type>
    <init>/sbin/init</init>
    <cmdline>console=ttyS0</cmdline>
  </os>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/usr/libexec/libvirt_lxc</emulator>
    <filesystem type='mount' accessmode='passthrough'>
      <source
dir='/home/stack/nova_state/instances/instance-00000078/rootfs'/>
      <target dir='/'/>
    </filesystem>
    <interface type='bridge'>
      <mac address='fa:16:3e:08:4f:b9'/>
      <source bridge='br100'/>
      <filterref filter='nova-instance-instance-00000078-fa163e084fb9'>
        <parameter name='DHCPSERVER' value='10.48.253.1'/>
        <parameter name='IP' value='10.48.253.2'/>
        <parameter name='PROJMASK' value='255.255.255.0'/>
        <parameter name='PROJNET' value='10.48.253.0'/>
      </filterref>
    </interface>
    <console type='pty'>
      <target type='lxc' port='0'/>
    </console>
  </devices>
</domain>


--
Qiu Yu
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